1. Field of the Invention
The present invention relates to an electrolyte and a rechargeable lithium battery, and more particularly, to a rechargeable lithium battery exhibiting good safety and discharge characteristics.
2. Description of the Related Art
Rechargeable lithium batteries have high working voltages and energy densities, and they exhibits good low-temperature performance. These advantages facilitate the increasing demands of portable electronics.
A rechargeable lithium battery includes an electrolyte including organic solvents. The organic solvents have a low flash point and high inflammability, so this battery has a shortcoming in that combustion can be caused by overcharging or heating it. Recently, attempts to use a mixture of an ester of formic acid including a halogen and a cyclic carbonic ester, a mixture of an ester of formic acid including a halogen and an ester halide, or a phosphoric ester as the organic solvent have been made, since these mixtures have self-fire extinguishing characteristics.
However, with the use of these organic solvents it is impossible to obtain sufficient discharge capacity, and they cause deterioration of the cycle life characteristics. These results are considered to occur because of the decomposition of the ester of formic acid including the halogen and phosphoric ester on a surface of the negative electrode. Such decomposition causes generation of gas and denaturing of the electrolyte, thereby deteriorating discharge capacity and cycle life characteristics.